Aluminum Adapter for Mossberg 500 590 Stock Top & both side Swivel Port & ScrewAdapter Description :This Adapter allows you to mount a pistol grip and stock to a Mossberg 500 series shotgun.Specs & Features: Aluminum Adapter For Mossberg 500 590 Fits Extension Tube 1 3/16″-16 TPIQD Sling Swivel Ports on Top and Both SideComes With Mounting Screw